Phew, lucky this thing does give great mileage. The state of California hasn't been a big fan of diesel in these past few years and whereas pretty much every filling station in Europe will have at least one diesel pump, that's not the case here, even on this industrialized stretch of Route One, just a few blocks inland from Venice and Santa Monica beaches.

After trying four gas stations of differing brands, I finally get to fill up european car's long-term VW Jetta 2.0 TDI and start this test properly. What follows will be the diary of a tankful of diesel: the miles, the motions, conveyance and convenience. That last aspect has already taken a hit by having to drive around looking for somewhere that sells diesel fuel.

Then the one pump stuck in a neglected corner of an otherwise large, glowing, pristine forecourt is sticky and smelly with the stuff. No disposable gloves around, so my first recommendation to anyone considering a TDI or its new, clean ilk would be to always keep a stash of wet wipes and tissues in the car. Even after I get home and wash my hands a couple of times, the smell is hard to shift. Luckily, such occurrences don't spring up that often. By the time I have to fill up again, this will become a distant memory because of all the life lived in between.

Trip zeroed, it reads 4.2 miles once I get home to Marina Del Rey. OK, it hasn't been the most auspicious of beginnings, but there's a long way to go and plenty of opportunity for this Jetta to wheedle its way into my affections-because the last one I drove (about two years ago) did not impress me. Although its gasoline-powered engine was punchy enough, the soft suspension was a big disappointment. From the admittedly short time spent in this driver's seat, the difference is obvious. There's so much more body control and a general feeling of being well sorted.

So with a firm yet comfortable chassis, leather-covered seats that answer to the same description and a thirst that has more in common with a recovering alcoholic than most American vehicles, the Jetta TDI is a perfect road trip car. An ideal excuse to take my wife, Claire, to Santa Barbara for the day. It's a wonderful drive, taking in a beautiful section of Pacific Coast Highway before joining Route 101 at Oxnard. The freeway still comes close to the shore, though, and it's sometimes possible to see dolphins breaking the ocean's surface, a pleasure best experienced by the passenger.

Playful sea mammals, however, aren't our focus today. Instead, we're going after butterflies. The Santa Barbara Museum of Natural History has a giant mesh marquee full of them. What's more, there are no feelings of guilt on our part. Since California has some of the toughest emissions laws on this beleaguered planet but still allows VW's clean diesel technology through the door, it's nice to know we're not making too much of an environmental impact, so these beautiful creatures might still live.

Everything's working well. With a lusty 236 lb-ft of torque just under the right foot, there's more than enough urge to reach freeway speeds, with plenty in reserve for overtaking. It all feels so effortless. The air conditioning performs exactly as it should, the steering has a fine balance of meatiness and precision, and the turning circle is a boon in tight places. There's the odd mild ticking noise in my left ear coming from the seatbelt apparatus, but it's tolerable. The only other fly in the ointment is that Claire, whose idea of hell would be working as a rally driver's navigator, is feeling a tad sick. It could be the car or maybe just one of those things. After a light meal followed by a couple of Dramamine, we head for home. By the time we park, the dash is reading 206.7 miles in red LEDs and the fuel gauge has hardly moved.

I wear a couple of hats. Writing about cars is one of them and playing guitar is the other. So the next trip is one of those times when my two worlds collide: a Sunday brunch gig in Valencia with the soul/blues/rock/jazz band I play in. The Jetta's trunk can easily take my amplifier and bag (full of cables, tools, stands and a couple of effects pedals), but I prefer to put my guitars (I always take two, just in case I break a string) on the back seat, even though they could probably have gone in the trunk too. If someone does slam into the back of me, at least my babies are better protected. I get like that about guitars.

There's always a chance some accident might happen on the dreaded 405, a freeway that runs north-south, although "runs" is way too optimistic. Most of the time it's a car park, plagued with pile-ups, and traffic moving at a geological rate, but early Sunday is easy enough. Even so, it takes a while to get fingers and brain warmed up-musicians aren't usually morning people. The gig is made all the more enjoyable by a party of people right near the band who are really into the music.

On the way back home, the 405 returns to form. It's now that I become more aware of the brakes. They feel as if they could use more initial bite. I thought the pads might be a bit worn since the car has over 17,000 miles on its odometer, but my ec colleagues tell me subsequently that they've always been this way. Stop-go-stop traffic doesn't help consumption figures at all, but one open stretch sees the trip computer reading an average of 40 mpg. Before taking out the key, I note the mileage: 287.5 miles and still plenty of fuel.

The next couple of days are spent running errands around west Los Angeles, Santa Monica (including changing 150 euros into dollars: $190, thanks very much) and up to my sister-in-law's place in rural, hilly Topanga. I quickly become grateful for two more of the Jetta's assets. The six-speed DSG gearbox is an absolute joy, whether using it as a normal automatic or shifting gears manually, especially on canyon roads. Shame there aren't steering wheel-mounted paddles, but the lever works. And Topangan topography usually turns radio signals into static, though satellite radio still comes through loud and clear.

One sound that's less welcome is the deep, sporty front lip scraping the ground. The lack of clearance means extra care is needed for going up steep driveways and the like. Still, after 341.5 miles, the fuel gauge has only just dipped below halfway. The weekly shop at Trader Joe's takes the distance to 358.3.

Two more gigs in Valencia, Friday and Saturday night. Tackling the 405 again at the tail-end of Friday's rush hour (in the aftermath of what was a fatal crash) makes me appreciate the Jetta's safety features, not just the standard-issue ESP and six airbags, but also that the Insurance Institute for Highway Safety (IIHS) has made it a top pick for 2009.

Driving home late at night, it's a nice cruise at 2250 rpm with average consumption comfortably in the mid-to-high 30s. And sorry if this sounds petty, but I love sweeping past Prius drivers while still achieving that kind of economy. The early hours of Sunday morning see 520.4 on the trip. Later that day, Claire and I go to see some friends in Hollywood, up near the famous Capitol Records building. At 530.3, I decide to fill up again. The fuel light hasn't come on yet, but I remember looking for diesel before and opt for taking the opportunity when it presents itself. In goes 13.551 gallons ($37.93), which gives us 39.13 mpg overall. The best figure on the trip computer was 45 mpg, an office record.

I wish I'd had the time and reason to drive to San Francisco. On such a trip, I'm sure a tankful could cover 600 miles. But the great thing about the Jetta is that every one of those miles would be enjoyable. It proves that fuel economy doesn't have to involve sacrificing the things that matter to drivers. Just remember the wet wipes.